Cathodic protection monitor

ABSTRACT

A device for attaching to piping systems or the like having a cathodic protection potential applied thereto and comprising a visual indicator operated by such potential for producing an alarm indication at an adjustable lower level of applied cathodic protection potential.

United States Patent Inventors Darrel I). Byerley Baldwin Park;

Robert B. Fisher, El Monte, both of, Calif. 837,200

June 27, I969 Sept. 7, 1971 Tinker and Rasor San Gabriel, Calif.

Appl. No. Filed Patented Assignee CATHODIC PROTECTION MONITOR 6 Claims,9 Drawing Figs.

US. Cl 340/249, 324/71 C Int. Cl G08b 21/00 Field of Search 204/147,196; 340/249, 248; 324/65 C, 65 CR, 65 CP, 71 C, 115, 29.5, 30, 133;307/95 [56] References Cited UNITED STATES PATENTS 1,807,903 6/1931Finley 307/95 2,086,737 7/1937 Pearson.... 324/71 C 3,266,027 8/1966Nichols 340/248 3,284,789 1 1/1966 Fisher 340/249 Primary Examiner-JohnW. Caldwell Assistant ExaminerDaniel Myer Attorney-Gregg & HendricsonABSTRACT: A device for attaching to piping systems or the like having acathodic protection potential applied thereto and comprising a visualindicator operated by such potential for producing an alarm indicationat an adjustable lower level of applied cathodic protection potential.

CATHODIC PROTECTION MONITOR BACKGROUND OF INVENTION It has long beenrealized that metallic elements of dissimilar metals which may, forexample, be buried in the ground are subject to disassociation. Moreparticularly, chemical reactions between dissimilar metals take place inwhich a current flows therebetween so as to establish a flow of chargedions and electrons therebetween. Metals of different reactivity whichare in contact with an electrically conductive path establish apotential difference, wherein one of such metals becomes an anode andthe other the cathode, so that electrons fiow to the anode and ions flowfrom the anode to the cathode. In this circumstance, the anode losesmetal, so as to become corroded. However, the other metal comprising thecathode, suffers no harmful effects.

Because of the general circumstances outlined in the preceding paragraphit has become common practice to establish a cathodic protection system,whereby metals otherwise subject to corrosion from electrolysis aremaintained at a relatively negative potential so as to form the cathodeof any electrolysis system, and thus suffer no corrosion ordeterioration.

One of the problems in cathodic protection systems is the monitoring ofthe protection potential applied to such systems. While it may initiallyseem that the mere application of an appropriate DC potential to pipes,cables, or the like, of a system would prevent occurrence of theelectrolysis problem, it has been found necessary to monitor theexistence of this potential. While many piping systems may be protectedby cathodic protection equipment, at least certain types of systems arecritically protected. Thus, for example, gas piping or other pipingsystems wherein highly volatile or explosive materials are carried bythe piping system must not only be protected against corrosion producedby electrolysis, but furthermore, must be periodically or evencontinuously checked to insure that no possible leak therein could ensuefrom electrolytic disassociation of metals. There have, in fact, beenestablished by various governmental bodies requirements for monitoringcathodic protection to preclude failure of electrolysis protectionsystems of particular types of piping systems.

A straightforward approach to the determination of the maintenance ofcathodic protection potential in any type of system is the periodicmeasurement of voltage and polarity thereof existing between the systemand the earth. Despite the fact that such an approach is quitestraightforward, it is inherently dangerous to the extent that checkingis only periodic and, furthermore, requires the use of particularinstrumentation and capabilities of those skilled in the art ofemploying and properly interpreting scientific instrumentation. A systemor detector for overcoming this basic difficulty is set forth in US.Pat. No. 3,284,789, entitled Cathodic Protection System Detector andassigned to the same assignee as the present application. The detectorof the above-noted patent provides a major advance in the field ofcathodic protection monitoring. However, it has been determined thateven this esiinple protector of the patent is beyond the comprehensionor at least full understanding of those wholly unskilled in the art. Thefield of electricity or electronics may be wholly foreign to thoseassigned the responsibility of operating or maintaining various types ofpiping systems such as, for example, natural gas piping systems. Themere reading of a meter may, in fact, require interpretative abilitiesbeyond the capabilities of personnel involved at a purely local level,wherein systems under cathodic protection are involved.

The present invention is particularly directed to the simplification ofcathodic protection monitoring or electrolysis protection monitoring,such that regardless of the skill of the one viewing the monitoringdevice or system there can be no question as to whether or not cathodicprotection is actually being provided to the system.

SUMMARY OF lNVENTlQN There is provided by the present invention ancxtrcmcly simplified version of a cathodic protection system in whichany person responsible for checking the system will be immediatelyapprised of the failure of cathodic protection thereof. In actuality,the present invention is a simplification of the invention covered bythe above-noted patent. This simplification has been made primarily forthe purpose of electrolysis protection monitoring, so that whollyuntrained personnel will be immediately apprised of cathodic protectionfailure without the necessity of such personnel reading or interpretingany type of meters or the like. Furthermore, the present invention isparticularly directed to the minimization of maintenance problems in themonitoring of electrolysis prevention systems.

While the various fields of engineering are undoubtedly interrelated inmany respects, it is a commonly acknowledged fact that those employed inparticular fields of engineering may be wholly untrained, insofar as thebasic field of engineering is concerned, and thus the equipment providedfor their utilization must be designed for unambiguous interpretation.While it may be considered, for example, that mechanical engineersdesigning and installing a natural gas system will be sufficientlycognizant of the principles of electrical engineering that they canproperly interpret electrical meters, or devices, it should not bepostulated that those ultimately charged with the responsibility ofmaintaining such a natural gas system will be equally qualified. Thus,we are here posed with the problem of an electrical or electronicphenomenon of basic importance in the field of mechanics or structuralengineering.

By the simplification of electrolysis protection monitoring, the presentinvention provides for a truly practical advance in the art, wherebysubstantially untrained personnel in the field of electricity will haveno hesitation or uncertainty in the interpretation of test resultsprovided to them, so far as action that should be taken thereon.

The present invention comprises a very simplified and straightforwardindicating device producing an unequivocable go or no go indication ofcathodic protection of any type of metallic system possibly subject toelectrolysis. More specifically, the invention provides a small metalhousing adapted to be physically mounted upon a pipe, cable, or thelike, of a metallic system and having a wire extending therefrom forelectrical connection to another portion of the system which iselectrically insulated from the portion engaged by the housing. There isprovided at the housing a flag indicator which exhibits at a facethereof either a white or a colored indication in response to thevoltage applied to the indicator, so that one viewing the, housing willimmediately be apprised of the presence or absence of requisite cathodicprotection. There is furthermore provided by the present inventionsimplified means for establishing the appropriate range of voltagecovered by the flag indicator thereof. This is herein provided by aterminal board located immediately beneath a removable cover of theabove-noted housing and having a jumper connector thereon extending froma first terminal of a tapped resistor into connection with any desiredother terminal thereof, in order to cut out the desired amount ofresistance in series with the flag indicator of the invention. All ofthe operative elements of the present invention disposed within thehousing thereof are potted by the provision of a plastic solidified inplace therein and retaining and supporting the above-noted terminalboard in position immediately beneath the removable cover plate of thehousing.

Further to the present invention, it is noted that in addition to theabove-noted patent of the common assignee hereof, there have beendeveloped certain advances in the general field of underground pipingprotection, such as that set forth in US. Pat. No. 1,807,903 which,however, is particularly directed to the discharging of potential froman insulated pipe. Such patent is only identified herein to positivelyidentify the basic differences between the concepts thereof and thoseofthe present invention. The present invention is directed to monitoringof the maintenance of a cathodic protection potential, while the basicidea and concepts of the abovenoted patent are the discharge ofelectrical charges that may be established between an insulated pipe andan electrical conductor. It is believed important to emphasize that thepresent invention is particularly directed to a simplification ofcathodic protection monitoring which is applicable to electricallyconducting systems in which cathodic protection is applied, and whichrequire a monitoring of the existence of such potential. The mechanicaland electrical details of the present invention have been simplified toa material extent, so as to provide for installation of the presentinvention by untrained personnel and the reading of the indicationproduced by this invention by untrained personnel. This, then, removesthe necessity of personal monitoring or reading of meters by thoseversed in the field of electricity, and truly extends the field ofcathodic protection systems to all possible applications regardless ofthe types of people involved in the installation, maintenance andinterpretation thereof.

DESCRIPTION OF FIGURES The present invention is illustrated as toparticular preferred embodiments thereof in the accompanying drawingswherein:

FIG. 1 is a side elevational view of a preferred embodiment of thepresent invention with a portion of the housing broken away toillustrate an internal connection;

FIG. 2 is an end elevational view of the embodiment of FIG.

FIG. 3 is a bottom plan view of the invention as illustrated in FIGS. 1and 2;

FIG. 4. is a sectional view, taken in the plane 44 of FIG. 2;

FIG. 5 is a top plan view of the embodiment of the invention illustratedin FIG. 1 with the cover removed, as indicated by the plane 5-5 of FIG.2;

FIG. 6 is a circuit diagram of an embodiment of the present invention;

FIG. 7 is a schematic illustration of a monitor in accordance with thepresent invention mounted upon a piping system for use in monitoringcathodic protection potential;

FIG. 8 is a circuit diagram of an embodiment of the present inventionemploying a semaphore indicator; and

FIG. 9 is an illustration of an alternative indicator face that may beemployed in the monitor of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring first to FIGS. 1 to 4 ofthe drawings, there will be seen to be provided a metal housing 11having a removable cover 12 which may be secured to the housing by meansof bolts 13 extending through the cover and threaded into the top of thehousing. The housing 11 is formed with an internal chamber 16 and thefront of the housing is formed with a hollow cylindrical extensiontherefrom, within which is fitted a flag indicator 17. This indicatormay comprise a conventional voltage indicating unit having, for example,a pair of openings 18 in the front face thereof with a flag, or thelike, moved into registry with these openings by the application of aminimal potential to the indicator. Removal of such voltage or loweringof same below this minimum causes the flag to move out of registry withthe openings so as to expose a colored background, preferably red. Theindicator face thus comprises some type of opaque mask with at least oneopening therethrough and adapted to provide a different color indicationat such opening for different voltages applied to the indicator.

The housing 11 is also formed with mounting means for ready attachmentof the housing to a metallic pipe, cable, or the like. Such mountingmeans may comprise a pair of lugs or feet 21 and 22 extending laterallyfrom opposite sides of the housing at the bottom thereof and havingopenings therethrough for the extension of bolts to engage a clamp.

These mounting feet 21 and 22 may be formed integrally with the housingin extension below same as well as laterally thereof, and a steppedindentation is provided between the feet underneath the housing, asshown at 23 in FIG. 1. Thus, the underside of the housing at thelaterally projecting feet forms one-half of a pipe clamp for readyattachment of the housing directly to a pipe. Naturally, alternativeconnections may be made in the instance wherein the pipe has such alarge diameter that the clamping portion of the housing is not adequateto properly fit thereon.

The indicator 17 extends into the housing chamber 16 and is thereprovided with at least two terminals 26 and 27. The indicator is adaptedto have a cathodic protection potential applied across these terminals.To this end, a conductor 28 is shown to be electrically connected to thehousing itself, which thus forms one electrical connection to a pipingsystem to be monitored for the presence of cathodic protectionpotential.

With regard to the other electrical connection of the monitor, referenceis made to FIGS. 5 and 6, where there will be seen to be illustratedresistance means 31 connected in series with the indicator 17 from theterminal 26 thereof to a conductor 32. This resistance means may, forexample, comprise a plurality of small resistors connected in series andhaving connecting taps extending from the junction of each pair ofresisters. The circuit also includes a jumper conductor 33 connected tothe conductor 32 at the outer end of the resistance means from theindicator and having connection means 34 thereon for connection to anyone of the taps of the resistance means. This jumper conductor 33 thusprovides for controllably establishing the amount of resistance inseries with the indicator between the connecting conductors 32 and 28.

Considering the physical embodiment of the wiring system, reference ismade to FIGS. 4 and 5, wherein it will be seen that there is providedherein an insulating terminal board 41 fitted into the housing chamber16 at the top thereof and having a plurality of terminals extendingupwardly therefrom. These terminals, numbered 42 to 49, comprise thetaps of the resistance means 31, and thus these same numbers areemployed in FIG. 6. The terminals 42 to 49 may be physically formed asthreaded elements extending upwardly from the terminal board 41, withthe jumper connector 33 permanently attached at one end to the terminal42. The other end of the jumper connector 33 may be formed as anapertured metal connector adapted to fit upon any one of the terminalsso that a small nut may be threaded onto the terminal above theconnector to firmly engage the jumper conductor end with the terminal.The resistance means 31 may be comprised as a plurality of smallresistors having the ends thereof soldered to separate tabs dependingfrom the terminals of the terminal board beneath the latter. Theconductor 32 extending from the end terminal 42 extends in insulatedrelationship through the bottom of the housing, as shown in FIG. 1. Thisconductor 32 may, for example, be jointed at a connector to a largerconductor within the housing, as illustrated, but electrically thisconductor extends from the housing for electrical connection to a clamp51 or electrical connector employed in the manner described below.

Further, with regard to the present invention, it is preferable toprovide a ripple filter in electrical connection across the indicator 17and this is shown in FIG. 6 to be accomplished by the connection of acapacitor 19 across the indicator. Such capacitor 19 is illustrated asto physical embodiment in FIG. 4, wherein it will be seen to have theends thereof electrically connected to the indicator terminals 26 and27, and to be disposed within the housing beneath the terminal board. Inorder to provide a firm support for the terminal board 41 and also toprotect the elements and connections within the housing, the entirechamber beneath the terminal board is filled with a potting material,i.e., an electrically insulating plastic which hardens in place. This isillustrated in FIG. 4 by conventional crosshatching. Upon hardening ofthis material, each of the elements, conductors, and the like, withinthe housing are fixed in position so that the possibilityof displacementof same or breaking of connections during usage of the monitor aresubstantially precluded.

Considering now an application of the present invention, reference ismade to FIG. 7. There is shown in FIG. 7 a piping system 61 which mayhave a portion thereof extending into the ground, as illustrated at 62.The piping system is formed of electrically conducting material and inorder to prevent electrolysis is supplied with a cathodic protectionpotential schematically illustrated in FIG. 7 as a battery 63. It willbe seen that potential applied to the system is such as to maintain theportion thereof in contact with the earth at a negative potential, so asto prevent any portion of the system from becoming an anode in anelectrolytic system. Such a cathodic protection system is conventionaland is, in fact, required for many types of installations. In suchsystems there is normally employed an insulated coupling shown in FIG. 7at 64, to prevent the application of the protection potential toportions of the system that may be subject to human contact. It isassumed in cathodic protection systems that some return path to groundis provided as, for example, through burners of a natural gas range, orthe like, and thus the monitor of the present invention is connectedacross the insulating coupling 64 of the system. The cathodic protectionpotential will appear across this insulating coupling, and the monitorof the present invention is provided for the purpose of continuouslyindicating the presence of requisite cathodic protection potential. Asshown in FIG. 7, the housing 11 may be physically mounted upon a pipe 66of the system on the ground side of the insulating coupling 64 in thesystem. This is shown to be accomplished by provision of another side ofa pipe clamp 67, fitting on the opposite side of a pipe from the housing11 and attached thereto by bolts 68 extending through the housing feetand engaging the lower clamp half 67. This, then, provides for physicalmounting of the housing and also for electrical connection of thehousing to the pipe 66, particularly at the stepped indentation 23 atthe bottom of the housing.

The insulated electrical conductor 32 extending from the housing iselectrically connected to a portion of the piping system on the oppositeside of the insulating coupling 64 from the housing. This may beaccomplished by a clamp 51 bolted or otherwise affixed to a pipe 69 ofthe system, such as shown in FIG. 7.

Considering now the operation of the present invention, it is firstnoted that the monitor is physically mounted upon the piping system inthe manner described above. With the cathodic protection potentialapplied to the system the cover of the housing 11 is then removed andthe jumper connector 33 attached to the lowest numbered terminal whichwill produce a voltage indication on the indicator 17. This will thenplace the greatest amount of resistance in series with the indicatorthat is possible to employ with the particular cathodic protectionpotential applied, and yet produce a showing by the indicator of theexistenceof cathodic protection potential. With the jumper connector 33firmly connected to the appropriate terminal 43 to 49, the cover is thenreturned to the housing and secured thereon. In this condition, with theindicator 17 of FIG. 2, there will normally be shown a white backgroundthrough the openings 18 in the face of the indicator. At any time thatthe cathodic protection potential decreases to the point where theindicator 17 is no longer actuated sufficiently to maintain a whiteflag, or the like, behind the openings 18 in the face of the indicator,such flag or flags will move away from the openings 18 to reveal acolored background, such as red. Thus, the present invention providesfor continuous monitoring of the existence of appropriate cathodicprotection potential to metallic systems and reading and understandingof the monitor can be accomplished by anyone, no matter how unskilled.At any time the indicator shows a red color through the openings in theface thereof, investigation should be made to determine the cause ofdifficulty which has produced the reduction in cathodic protectionpotential on the system. Although it may be necessary in theinvestigation and correction of difficulties to employ trainedpersonnel, it is certainly not necessary with the present invention torequire any type of specialized training to read the monitor hereof.Even though one checking the system may be wholly uninformed about theproblems of cathodic protection, they will be immediately apprised ofsome type of difficulty in the system by noting the red color appearingin the face of the indicator. There is thus established by the presentinvention a go-no go indication, wherein no meter readings are requiredand no external indicating or detecting equipment is employed. Themonitor of the present invention is adapted for substantially permanentattachment to piping or cable systems requiring cathodic protection.

It is to be appreciated that numerous variations in the presentinvention are possible, and thus, for example, as illustrated in FIG. 8,a semaphore-type indicator 71 may be employed in place of the flagindicator described above. The circuitry in this circumstance wouldremain the same. Similarly, it is possible for the indicator to bealternatively comprised even to the extent of having a meter face. Itis, however, provided in accordance with the present invention, that ago-no go" indication shall be provided by the invention. Thus, in FIG. 9there is illustrated the face 81 of an indicator 82 connected asdescribed above, and having a needle or arm 83 movable thereacross, inaccordance with many types of meters. In order to preclude the necessityof meter reading, the present invention provides a mask 84 across aportion of the meter face, so that the needle 83 only becomes visiblewhen it moves beyond the mask. The left of the face in FIG. 8 may beconsidered the mask aperture, and the needle 83 may be brightly coloredso that its presence at the left of the face would be immediatelyapparent to one viewing the indicator.

Again, it is noted that simplification of cathodic protection monitoringis a major aim in the present invention. Variations of the inventionfrom the specifically described and illustrated details are, of course,possible. Reference is made to the appended claims for a precisedefinition of the invention.

We claim:

1. An electrolysis protection monitor for use with a metallic systemhaving a cathodic protection potential applied thereto comprising:

a housing having a removable cover,

a flag voltage indicator mounted in a wall of said housing with a faceopen to the exterior of the housing and terminals within the housing,

electrical resistance means having a plurality of taps thereon connectedat a first end to a first indicator terminal,

means mounting said resistance means in said housing with the tapsthereof adjacent said cover,

a jumper conductor connected to a second end of said resistance meansand having connection means for selective connection to resistance tapsto establish the effective value of resistance thereof, and

conductors extending from a second indicator terminal and from thesecond end of said resistance means for electrical contact with a pipingsystem on opposite sides of an electrically insulating portion thereof.

2. The monitor of claim 1 further defined by a terminal board disposedwithin said housing adjacent said cover with terminals thereof facingthe cover, means mounting said resistance means on the opposite side ofsaid board from said terminals with said taps comprised by saidterminals and said jumper conductor being connected to one end terminalof said board and the connection means being adapted for removableengagement with said terminals on said board.

3. The monitor of claim 1 further defined by said flag voltage indicatorincluding a face having a mask with at least one opening therethroughand voltage-responsive movable means mounted to move into registry withsaid mask opening with reduction of voltage applied to the indicator.

4. The monitor of claim 1 further defined by said housing being formedof metal with extensions for attachment of the housing to a pipe or thelike, and said conductors extending in place all elements within thehousing.

6. The monitor of claim 1 further defined by said indicator having ameter face with an arm movable thereacross indicating voltage applied tothe indicator and an opaque mask extending over a portion of said meterface whereby said indicator arm is only visible for a predetermined lowvoltage applied to the indicator.

1. An electrolysis protection monitor for use with a metallic systemhaving a cathodic protection potential applied thereto comprising: ahousing having a removable cover, a flag voltage indicator mounted in awall of said housing with a face open to the exterior of the housing andterminals within the housing, electrical resistance means having aplurality of taps thereon connected at a first end to a first indicatorterminal, means mounting said resistance means in said housing with thetaps thereof adjacent said cover, a jumper conductor connected to asecond end of said resistance means and having connection means forselective connection to resistance taps to establish the effective valueof resistance thereof, and conductors extending from a second indicatorterminal and from the second end of said resistance means for electricalcontact with a piping system on opposite sides of an electricallyinsulating portion thereof.
 2. The monitor of claim 1 further defined bya terminal board disposed within said housing adjacent said cover withterminals thereof facing the cover, means mounting said resistance meanson the opposite side of said board from said terminals with said tapscomprised by said terminals and said jumper conductor being connected toone end terminal of said board and the connection means being adaptedfor removable engagement with said terminals on said board.
 3. Themonitor of claim 1 further defined by said flag voltage indicatorincluding a face having a mask with at least one opening therethroughand voltage-responsive movable means mounted to move into registry withsaid mask opening with reduction of voltage applied to the indicator. 4.The monitor of claim 1 further defined by said housing being formed ofmetal with extensions for attachment of the housing to a pipe or thelike, and said conductors extending first from the second indicatorterminal into electrical contact with the housing and second from thesecond end of said resistance means through the housing wall ininsulated relation thereto for electrical connection to a pipe of thesystem at a distance from the housing.
 5. The monitor of claim 2 furtherdefined by the interior of said housing beneath said terminal boardbeing filled with a plastic solidified in place for holding the terminalboard in place adjacent said housing cover and surrounding and fixing inplace all elements within the housing.
 6. The monitor of claim 1 furtherdefined by said indicator having a meter face with an arm movablethereacross indicating voltage applied to the indicator and an opaquemask extending over a portion of said meter face whereby said indicatorarm is only visible for a predetermined low voltage applied to theindicator.